Ink ejection nozzle with oscillator and shutter arrangement

ABSTRACT

An ink ejection nozzle has an ink reservoir with an oscillator configured to oscillate ink pressure in the reservoir. A wafer assembly defines an ink supply channel in fluid communication with the ink reservoir. A nozzle chamber structure on the wafer assembly defines a nozzle chamber in fluid communication with the ink supply channel. An ink ejection port is in fluid communication with the nozzle chamber. A shutter is positioned in the nozzle chamber and is configured to shut the ink ejection port to the ejection of ink from the nozzle chamber.

CROSS REFERENCES TO RELATED APPLICATIONS

This is a Continuation Application of U.S. application Ser. No. 11/525,859 filed on Sep. 25, 2006, now issued U.S. Pat. No. 7,270,399, which is a Continuation Application of U.S. application Ser. No. 11/144,804 filed Jun. 6, 2005, now granted U.S. Pat. No. 7,144,098, which is a continuation of U.S. application Ser. No. 10/693,990 filed Oct. 28, 2003, now issued as U.S. Pat. No. 6,929,352, which is a continuation of U.S. application Ser. No. 10/302,606 filed on Nov. 23, 2002, now issued U.S. Pat. No. 6,644,767, which is a Continuation of U.S. application Ser. No. 09/855,094 filed May 14, 2001, now issued U.S. Pat. No. 6,485,123 which is a Continuation-in-part of U.S. application Ser. No. 09/112,815 filed on Jul. 10, 1998, now issued U.S. Pat. No. 6,247,792, all of which is herein incorporated by reference.

The following Australian provisional patent applications are hereby incorporated by reference. For the purposes of location and identification, U.S. patents/patent applications identified by their U.S. patent/patent applications claim the right of priority.

CROSS-REFERENCED US PATENT/PATENT AUSTRALIAN APPLICATION (CLAIMING PROVISIONAL RIGHT OF PRIORITY FROM PATENT AUSTRALIAN PROVISIONAL DOCKET APPLICATION NO. APPLICATION) NO. PO7991 6750901 ART01US PO8505 6476863 ART02US PO7988 6788336 ART03US PO9395 6322181 ART04US PO8017 6597817 ART06US PO8014 6227648 ART07US PO8025 6727948 ART08US PO8032 6690419 ART09US PO7999 6727951 ART10US PO8030 6196541 ART13US PO7997 6195150 ART15US PO7979 6362868 ART16US PO7978 6831681 ART18US PO7982 6431669 ART19US PO7989 6362869 ART20US PO8019 6472052 ART21US PO7980 6356715 ART22US PO8018 6894694 ART24US PO7938 6636216 ART25US PO8016 6366693 ART26US PO8024 6329990 ART27US PO7939 6459495 ART29US PO8501 6137500 ART30US PO8500 6690416 ART31US PO7987 7050143 ART32US PO8022 6398328 ART33US PO8497 7110024 ART34US PO8020 6431704 ART38US PO8504 6879341 ART42US PO8000 6415054 ART43US PO7934 6665454 ART45US PO7990 6542645 ART46US PO8499 6486886 ART47US PO8502 6381361 ART48US PO7981 6317192 ART50US PO7986 6850274 ART51US PO7983 09/113054 ART52US PO8026 6646757 ART53US PO8028 6624848 ART56US PO9394 6357135 ART57US PO9397 6271931 ART59US PO9398 6353772 ART60US PO9399 6106147 ART61US PO9400 6665008 ART62US PO9401 6304291 ART63US PO9403 6305770 ART65US PO9405 6289262 ART66US PP0959 6315200 ART68US PP1397 6217165 ART69US PP2370 6786420 DOT01US PO8003 6350023 Fluid01US PO8005 6318849 Fluid02US PO8066 6227652 IJ01US PO8072 6213588 IJ02US PO8040 6213589 IJ03US PO8071 6231163 IJ04US PO8047 6247795 IJ05US PO8035 6394581 IJ06US PO8044 6244691 IJ07US PO8063 6257704 IJ08US PO8057 6416168 IJ09US PO8056 6220694 IJ10US PO8069 6257705 IJ11US PO8049 6247794 IJ12US PO8036 6234610 IJ13US PO8048 6247793 IJ14US PO8070 6264306 IJ15US PO8067 6241342 IJ16US PO8001 6247792 IJ17US PO8038 6264307 IJ18US PO8033 6254220 IJ19US PO8002 6234611 IJ20US PO8068 6302528 IJ21US PO8062 6283582 IJ22US PO8034 6239821 IJ23US PO8039 6338547 IJ24US PO8041 6247796 IJ25US PO8004 6557977 IJ26US PO8037 6390603 IJ27US PO8043 6362843 IJ28US PO8042 6293653 IJ29US PO8064 6312107 IJ30US PO9389 6227653 IJ31US PO9391 6234609 IJ32US PP0888 6238040 IJ33US PP0891 6188415 IJ34US PP0890 6227654 IJ35US PP0873 6209989 IJ36US PP0993 6247791 IJ37US PP0890 6336710 IJ38US PP1398 6217153 IJ39US PP2592 6416167 IJ40US PP2593 6243113 IJ41US PP3991 6283581 IJ42US PP3987 6247790 IJ43US PP3985 6260953 IJ44US PP3983 6267469 IJ45US PO7935 6224780 IJM01US PO7936 6235212 IJM02US PO7937 6280643 IJM03US PO8061 6284147 IJM04US PO8054 6214244 IJM05US PO8065 6071750 IJM06US PO8055 6267905 IJM07US PO8053 6251298 IJM08US PO8078 6258285 IJM09US PO7933 6225138 IJM10US PO7950 6241904 IJM11US PO7949 6299786 IJM12US PO8060 6866789 IJM13US PO8059 6231773 IJM14US PO8073 6190931 IJM15US PO8076 6248249 IJM16US PO8075 6290862 IJM17US PO8079 6241906 IJM18US PO8050 6565762 IJM19US PO8052 6241905 IJM20US PO7948 6451216 IJM21US PO7951 6231772 IJM22US PO8074 6274056 IJM23US PO7941 6290861 IJM24US PO8077 6248248 IJM25US PO8058 6306671 IJM26US PO8051 6331258 IJM27US PO8045 6110754 IJM28US PO7952 6294101 IJM29US PO8046 6416679 IJM30US PO9390 6264849 IJM31US PO9392 6254793 IJM32US PP0889 6235211 IJM35US PP0887 6491833 IJM36US PP0882 6264850 IJM37US PP0874 6258284 IJM38US PP1396 6312615 IJM39US PP3989 6228668 IJM40US PP2591 6180427 IJM41US PP3990 6171875 IJM42US PP3986 6267904 IJM43US PP3984 6245247 IJM44US PP3982 6315914 IJM45US PP0895 6231148 IR01US PP0869 6293658 IR04US PP0887 6614560 IR05US PP0885 6238033 IR06US PP0884 6312070 IR10US PP0886 6238111 IR12US PP0877 6378970 IR16US PP0878 6196739 IR17US PP0883 6270182 IR19US PP0880 6152619 IR20US PO8006 6087638 MEMS02US PO8007 6340222 MEMS03US PO8010 6041600 MEMS05US PO8011 6299300 MEMS06US PO7947 6067797 MEMS07US PO7944 6286935 MEMS09US PO7946 6044646 MEMS10US PP0894 6382769 MEMS13US

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to an ink jet printer for use with a pulsating pressure ink supply.

BACKGROUND OF THE INVENTION

Many different types of printing have been invented, a large number of which are presently in use. The known forms of print have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.

In recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles has become increasingly popular primarily due to its inexpensive and versatile nature.

Many different techniques on ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, “Non-Impact Printing: Introduction and Historical Perspective”, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).

Ink Jet printers themselves come in many different types. The utilisation of a continuous stream ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electro-static ink jet printing.

U.S. Pat. No. 3,596,275 by Sweet also discloses a process of a continuous ink jet printing including the step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still used by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al)

Piezoelectric ink jet printers are also one form of commonly used ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which discloses a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) which discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 which discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.

Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclose ink jet printing techniques rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices using the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumables.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a printer including a printhead with an ink jet printhead chip, wherein the printhead chip comprises:

a substrate that incorporates drive circuitry,

a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising

-   -   nozzle chamber walls that define a nozzle chamber and an ink         ejection port in fluid communication with the nozzle chamber,         the nozzle chamber being in fluid communication with an ink         supply channel through the substrate for supplying the nozzle         chamber with ink;     -   a closure that is operatively positioned with respect to the ink         supply channel, the closure being displaceable between a closed         position in which the closure closes the ink supply channel and         an open position in which ink is permitted to flow into the         nozzle chamber; and     -   an actuator that is connected to the drive circuitry and the         closure so that, on receipt of an electrical signal from the         drive circuitry, the actuator can act to displace the closure         between the closed and open positions;

an ink reservoir in fluid communication with each ink supply channel; and

a source of oscillating pressure that imparts an oscillating pressure to ink in the reservoir, so that, when the closure is displaced into the open position, a drop of ink can be ejected from the ink ejection port.

an ink jet printhead chip which comprises:

a substrate that incorporates drive circuitry,

a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising

-   -   -   nozzle chamber walls that define a nozzle chamber and an ink             ejection port in fluid communication with the nozzle             chamber, the nozzle chamber being in fluid communication             with an ink supply channel through the substrate for             supplying the nozzle chamber with ink;         -   a closure that is operatively positioned with respect to the             ink supply channel, the closure being displaceable between a             closed position in which the closure closes the ink supply             channel and an open position in which ink is permitted to             flow into the nozzle chamber; and         -   an actuator that is connected to the drive circuitry and the             closure so that, on receipt of an electrical signal from the             drive circuitry, the actuator can act to displace the             closure between the closed and open positions;

an ink reservoir in fluid communication with each ink supply channel; and

a source of oscillating pressure that imparts an oscillating pressure to ink in the reservoir, so that, when the closure is displaced into the open position, a drop of ink can be ejected from the ink ejection port.

Each actuator may be elongate and may be anchored at one end to the substrate. The actuator may be shaped so that, in a rest condition, the actuator encloses an arc. The actuator may include a heating portion that is capable of being heated on receipt of an electrical signal to expand, the heating portion being configured so that, when the portion is heated, the resultant expansion of the portion causes the actuator to straighten at least partially and a subsequent cooling of the portion causes the actuator to return to its rest condition thereby displacing the closure between the closed and open positions.

Each actuator may include a body portion that is of a resiliently flexible material having a coefficient of thermal expansion which is such that the material can expand to perform work when heated. The heating portion may be positioned in the body portion and may define a heating circuit of a suitable metal.

The heating circuit may include a heater and a return trace. The heater may be positioned proximate an inside edge of the body portion and the return trace may be positioned outwardly of the heater, so that an inside region of the body portion is heated to a relatively greater extent with the result that the inside region expands to a greater extent than a remainder of the body portion.

A serpentine length of said suitable material may define the heater.

The body portion may be of polytetrafluoroethylene and the heating circuit may be of copper.

Each actuator may define a coil that partially uncoils when the heating portion expands.

The actuator and the closure may be positioned within the nozzle chamber.

In accordance with a second aspect of the present invention, there is provided an ink jet nozzle comprising an ink ejection port for the ejection of ink, an ink supply with an oscillating ink pressure interconnected to the ink ejection port, a shutter mechanism interconnected between the ink supply and the ink ejection port, which blocks the ink ejection port, and an actuator mechanism for moving the shutter mechanism on demand away from the ink ejection port so as to allow for the ejection of ink on demand from the ink ejection port.

In another embodiment of the invention, there is provided a method of operating an ink jet printhead that includes a plurality of nozzle arrangements and an ink reservoir, each nozzle arrangement having:

-   -   a nozzle chamber and an ink ejection port in fluid communication         with the nozzle chamber, and     -   a closure that is operatively positioned with respect to the ink         ejection port, the closure being displaceable between open and         closed positions to open and close the ink ejection port,         respectively,     -   the ink reservoir in fluid communication with the nozzle         chambers, the method comprising the steps of:     -   maintaining each closure in the closed position;     -   subjecting ink in the ink reservoir and thus each nozzle chamber         to an oscillating pressure,     -   selectively and independently displacing each closure into the         open position so that an ink droplet is ejected from the         respective ink ejection port as a result of the oscillating         pressure.

Further, the actuator preferably comprises a thermal actuator which is activated by the heating of one side of the actuator. Preferably the actuator has a coiled form and is uncoiled upon heating. The actuator includes a serpentine heater element encased in a material having a high coefficient of thermal expansion. The serpentine heater concertinas upon heating. Advantageously, the actuator includes a thick return trace for the serpentine heater element. The material in which the serpentine heater element is encased comprises polytetrafluoroethylene. The actuator is formed within a nozzle chamber which is formed on a silicon wafer and ink is supplied to the ejection port through channels etched through the silicon wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with the preferred embodiment;

FIG. 2 is a perspective view, partly in section, of a single ink jet nozzle constructed in accordance with the preferred embodiment;

FIG. 3 provides a legend of the materials indicated in FIGS. 4 to 16;

FIG. 4 to FIG. 16 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle; and

FIG. 17 shows a schematic, sectional end view of part of an ink jet nozzle array showing two nozzle arrangements of the array;

FIG. 18 shows the array with ink being ejected from one of the nozzle arrangements;

FIG. 19 shows a schematic side view of re-filling of the nozzle of the first nozzle arrangement; and

FIG. 20 shows operation of the array preceding commencement of ink ejection from the second of the illustrated nozzle arrangements.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the preferred embodiment, an oscillating ink reservoir pressure is used to eject ink from ejection nozzles. Each nozzle has an associated shutter which normally blocks the nozzle. The shutter is moved away from the nozzle by an actuator whenever an ink drop is to be fired.

Turning initially to FIG. 1, there is illustrated in exploded perspective a single ink jet nozzle 10 as constructed in accordance with the principles of the present invention. The exploded perspective illustrates a single ink jet nozzle 10. Ideally, the nozzles are formed as an array on a silicon wafer 12. The silicon wafer 12 is processed so as to have two level metal CMOS circuitry which includes metal layers and glass layers 13 and which are planarised after construction. The CMOS metal layer has a reduced aperture 14 for the access of ink from the back of silicon wafer 12 via an ink supply channel 15.

A bottom nitride layer 16 is constructed on top of the CMOS layer 13 so as to cover, protect and passivate the CMOS layer 13 from subsequent etching processes. Subsequently, there is provided a copper heater layer 18 which is sandwiched between two polytetrafluoroethylene (PTFE) layers 19,20. The copper layer 18 is connected to lower CMOS layer 13 through vias 25,26. The copper layer 18 and PTFE layers 19,20 are encapsulated within nitride borders e.g. 28 and nitride top layer 29 which includes an ink ejection port 30 in addition to a number of sacrificial etched access holes 32 which are of a smaller dimension than the ejection port 30 and are provided for allowing access of a etchant to lower sacrificial layers thereby allowing the use of the etchant in the construction of layers, 18,19,20 and 28.

Turning now to FIG. 2, there is shown a cutaway perspective view of a fully constructed ink jet nozzle 10. The ink jet nozzle uses an oscillating ink pressure to eject ink from ejection port 30. Each nozzle has an associated shutter 31 which normally blocks it. The shutter 31 is moved away from the ejection port 30 by an actuator 35 whenever an ink drop is to be fired.

The ports 30 are in communication with ink chambers which contain the actuators 35. These chambers are connected to ink supply channels 15 which are etched through the silicon wafer. The ink supply channels 15 are substantially wider than the ports 30, to reduce the fluidic resistance to the ink pressure wave. The ink channels 15 are connected to an ink reservoir. An ultrasonic transducer (for example, a piezoelectric transducer) is positioned in the reservoir. The transducer oscillates the ink pressure at approximately 100 KHz. The ink pressure oscillation is sufficient that ink drops would be ejected from the nozzle were it not blocked by the shutter 31.

The shutters are moved by a thermoelastic actuator 35. The actuators are formed as a coiled serpentine copper heater 23 embedded in polytetrafluoroethylene (PTFE) 19/20. PTFE has a very high coefficient of thermal expansion (approximately 770×10⁻⁶). The current return trace 22 from the heater 23 is also embedded in the PTFE actuator 35, the current return trace 22 is made wider than the heater trace 23 and is not serpentine. Therefore, it does not heat the PTFE as much as the serpentine heater 23 does. The serpentine heater 23 is positioned along the inside edge of the PTFE coil, and the return trace is positioned on the outside edge. When actuated, the inside edge becomes hotter than the outside edge, and expands more. This results in the actuator 35 uncoiling.

The heater layer 23 is etched in a serpentine manner both to increase its resistance, and to reduce its effective tensile strength along the length of the actuator. This is so that the low thermal expansion of the copper does not prevent the actuator from expanding according to the high thermal expansion characteristics of the PTFE.

By varying the power applied to the actuator 35, the shutter 31 can be positioned between the fully on and fully off positions. This may be used to vary the volume of the ejected drop. Drop volume control may be used either to implement a degree of continuous tone operation, to regulate the drop volume, or both.

When data signals distributed on the printhead indicate that a particular nozzle is turned on, the actuator 35 is energized, which moves the shutter 31 so that it is not blocking the ink chamber. The peak of the ink pressure variation causes the ink to be squirted out of the nozzle 30. As the ink pressure goes negative, ink is drawn back into the nozzle, causing drop break-off. The shutter 31 is kept open until the nozzle is refilled on the next positive pressure cycle. It is then shut to prevent the ink from being withdrawn from the nozzle on the next negative pressure cycle.

Each drop ejection takes two ink pressure cycles. Preferably half of the nozzles 10 should eject drops in one phase, and the other half of the nozzles should eject drops in the other phase. This minimises the pressure variations which occur due to a large number of nozzles being actuated.

Referring to FIGS. 17 to 20, the operation of the printhead is described in greater detail. The printhead comprises an array of nozzle arrangements or nozzles 10, two of which are shown as 10.1 and 10.2 in FIG. 17. Each nozzle arrangement 10 has a chamber 58 in which its associated shutter 31 is arranged.

Each chamber 58 is in communication with an ink reservoir 60 via an ink supply channel 36. An ultrasonic transducer in the form of a piezoelectric transducer 62 is arranged n the ink reservoir 60.

As described above, each ink drop ejection takes two ink pressure cycles. The two ink pressure cycles are referred to as a phase. Half of the nozzles 10 should eject ink drops 64 (FIG. 18) in one phase with the other half of the nozzles ejecting ink drops in the other phase.

Consequently, as shown in FIG. 17 of the drawings, the shutter 31.2 of the nozzle 10.2 is in an open position while the shutter 31.1 of the nozzle 10.1 is in its closed position. It will be appreciated that the nozzle 10.2 represents all the open nozzles of the array of the printhead while the nozzle 10.1 represents all the closed nozzles of the array of the printhead.

In a first pressure cycle, the transducer 62 is displaced in the direction of arrows 66 imparting positive pressure to the ink 57 in the reservoir 60 and, via the channels 36, the chambers 58 of the nozzles 10. Due to the fact that the shutter 31.2 of the nozzle 10.2 is open, ink in the ink ejection port 30.2 bulges outwardly as shown by the meniscus 68. After a predetermined interval, the transducer 62 reverses direction to move in the direction of arrows 70 as shown in FIG. 18 of the drawings. This causes necking, as shown at 72, resulting in separation of the ink drop 64 due to a first negative going pressure cycle imparted to the ink 57.

In the second positive pressure cycle, as shown in FIG. 19 of the drawings, with the transducer moving again in the direction of arrow 66, the positive pressure applied to the ink results in a refilling of the chamber 58.2 of the nozzle 10.2. It is to be noted that the shutter 31.2 is still in an open position with the shutter 31.1 still being in a closed position. In this cycle, no ink is ejected from either nozzle 10.1 or 10.2.

Before the second negative pressure cycle, as shown in FIG. 20 of the drawings, the shutter 31.2 moves to its closed position. Then, as the transducer 62 again moves in the direction of arrows 70 to impart negative pressure to the ink 57, a slight concave meniscus 74 is formed at both ink ejection ports 30.1 and 30.2 However, due to the fact that both shutters 31.1 and 31.2 are closed, withdrawal of ink from the chambers 58.1 and 58.2 of the nozzles 10.1 and 10.2, respectively, is inhibited.

The amplitude of the ultrasonic transducer can be altered in response to the viscosity of the ink (which is typically affected by temperature), and the number of drops which are to be ejected in the current cycle. This amplitude adjustment can be used to maintain consistent drop size in varying environmental conditions.

The drop firing rate can be around 50 KHz. The ink jet head is suitable for fabrication as a monolithic page wide printhead. FIG. 2 shows a single nozzle of a 1600 dpi printhead in “up shooter” configuration.

Returning again to FIG. 1, one method of construction of the ink jet print nozzles 10 will now be described. Starting with the bottom wafer layer 12, the wafer is processed so as to add CMOS layers 13 with an aperture 14 being inserted. The nitride layer 16 is laid down on top of the CMOS layers so as to protect them from subsequent etchings.

A thin sacrificial glass layer is then laid down on top of nitride layers 16 followed by a first PTFE layer 19, the copper layer 18 and a second PTFE layer 20. Then a sacrificial glass layer is formed on top of the PTFE layer and etched to a depth of a few microns to form the nitride border regions 28. Next the top layer 29 is laid down over the sacrificial layer using the mask for forming the various holes including the processing step of forming the rim 40 on nozzle 30. The sacrificial glass is then dissolved away and the channel 15 formed through the wafer by means of utilisation of high density low pressure plasma etching such as that available from Surface Technology Systems.

One form of detailed manufacturing process which can be used to fabricate monolithic ink jet printheads operating in accordance with the principles taught by the present embodiment can proceed using the following steps:

1. Using a double sided polished wafer 12, complete drive transistors, data distribution, and timing circuits using a 0.5 micron, one poly, 2 metal CMOS process 13. The wafer is passivated with 0.1 microns of silicon nitride 16. This step is shown in FIG. 4. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. FIG. 3 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.

2. Etch nitride and oxide down to silicon using Mask 1. This mask defines the nozzle inlet below the shutter. This step is shown in FIG. 5.

3. Deposit 3 microns of sacrificial material 50 (e.g. aluminum or photosensitive polyimide)

4. Planarize the sacrificial layer to a thickness of 1 micron over nitride. This step is shown in FIG. 6.

5. Etch the sacrificial layer using Mask 2. This mask defines the actuator anchor point 51. This step is shown in FIG. 7.

6. Deposit 1 micron of PTFE 52.

7. Etch the PTFE, nitride, and oxide down to second level metal using Mask 3. This mask defines the heater vias 25, 26. This step is shown in FIG. 8.

8. Deposit the heater 53, which is a 1 micron layer of a conductor with a low Young's modulus, for example aluminum or gold.

9. Pattern the conductor using Mask 4. This step is shown in FIG. 9.

10. Deposit 1 micron of PTFE 54.

11. Etch the PTFE down to the sacrificial layer using Mask 5. This mask defines the actuator and shutter This step is shown in FIG. 10.

12. Wafer probe. All electrical connections are complete at this point, bond pads are accessible, and the chips are not yet separated.

13. Deposit 3 microns of sacrificial material 55. Planarize using CMP

14. Etch the sacrificial material using Mask 6. This mask defines the nozzle chamber wall 28. This step is shown in FIG. 11.

15. Deposit 3 microns of PECVD glass 56.

16. Etch to a depth of (approx.) 1 micron using Mask 7. This mask defines the nozzle rim 40. This step is shown in FIG. 12.

17. Etch down to the sacrificial layer using Mask 6. This mask defines the roof of the nozzle chamber, the nozzle 30, and the sacrificial etch access holes 32. This step is shown in FIG. 13.

18. Back-etch completely through the silicon wafer (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 7. This mask defines the ink inlets 15 which are etched through the wafer. The wafer is also diced by this etch. This step is shown in FIG. 14.

19. Etch the sacrificial material. The nozzle chambers are cleared, the actuators freed, and the chips are separated by this etch. This step is shown in FIG. 15.

20. Mount the printheads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer. The package also includes a piezoelectric actuator attached to the rear of the ink channels. The piezoelectric actuator provides the oscillating ink pressure required for the ink jet operation.

21. Connect the printheads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.

22. Hydrophobize the front surface of the printheads.

23. Fill the completed printheads with ink 57 and test them. A filled nozzle is shown in FIG. 16.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the preferred embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

The presently disclosed ink jet printing technology is potentially suited to a wide range of printing systems including: colour and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers, high speed pagewidth printers, notebook computers with inbuilt pagewidth printers, portable colour and monochrome printers, colour and monochrome copiers, colour and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic ‘minilabs’, video printers, PhotoCD printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal ink jet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per printhead, but is a major impediment to the fabrication of pagewidth printheads with 19,200 nozzles.

Ideally, the ink jet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new ink jet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systems described below with differing levels of difficulty. Forty-five different ink jet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table under the heading Cross References to Related Applications.

The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems.

For ease of manufacture using standard process equipment, the printhead is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the printhead is 100 mm long, with a width which depends upon the ink jet type. The smallest printhead designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The printheads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the printhead by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The printhead is connected to the camera circuitry by tape automated bonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation of individual ink jet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of ink jet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of ink jet nozzle. While not all of the possible combinations result in a viable ink jet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain ink jet types have been investigated in detail. These are designated IJ01 to IJ45 above which matches the docket numbers in the table under the heading Cross References to Related Applications.

Other ink jet configurations can readily be derived from these forty-five examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into ink jet printheads with characteristics superior to any currently available ink jet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, a print technology may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) Description Advantages Disadvantages Examples Thermal An electrothermal Large force High power Canon bubble heater heats the ink generated Ink carrier Bubblejet 1979 to above boiling Simple limited to water Endo et al GB point, transferring construction Low efficiency patent 2,007,162 significant heat to No moving High Xerox heater- the aqueous ink. A parts temperatures in-pit 1990 bubble nucleates and Fast operation required Hawkins et al quickly forms, Small chip area High U.S. Pat. No. 4,899,181 expelling the ink. required for mechanical stress Hewlett- The efficiency of the actuator Unusual Packard TIJ 1982 process is low, with materials required Vaught et al U.S. Pat. No. typically less than Large drive 4,490,728 0.05% of the transistors electrical energy Cavitation being transformed causes actuator into kinetic energy failure of the drop. Kogation reduces bubble formation Large print heads are difficult to fabricate Piezoelectric A piezoelectric Low power Very large area Kyser et al U.S. Pat. No. crystal such as lead consumption required for 3,946,398 lanthanum zirconate Many ink types actuator Zoltan U.S. Pat. No. (PZT) is electrically can be used Difficult to 3,683,212 activated, and either Fast operation integrate with 1973 Stemme expands, shears, or High efficiency electronics U.S. Pat. No. 3,747,120 bends to apply High voltage Epson Stylus pressure to the ink, drive transistors Tektronix ejecting drops. required IJ04 Full pagewidth print heads impractical due to actuator size Requires electrical poling in high field strengths during manufacture Electro- An electric field is Low power Low maximum Seiko Epson, strictive used to activate consumption strain (approx. Usui et all JP electrostriction in Many ink types 0.01%) 253401/96 relaxor materials can be used Large area IJ04 such as lead Low thermal required for lanthanum zirconate expansion actuator due to titanate (PLZT) or Electric field low strain lead magnesium strength required Response speed niobate (PMN). (approx. 3.5 V/μm) is marginal (~ 10 μs) can be High voltage generated without drive transistors difficulty required Does not Full pagewidth require electrical print heads poling impractical due to actuator size Ferroelectric An electric field is Low power Difficult to IJ04 used to induce a consumption integrate with phase transition Many ink types electronics between the can be used Unusual antiferroelectric Fast operation materials such as (AFE) and (<1 μs) PLZSnT are ferroelectric (FE) Relatively high required phase. Perovskite longitudinal strain Actuators materials such as tin High efficiency require a large modified lead Electric field area lanthanum zirconate strength of around titanate (PLZSnT) 3 V/μm can be exhibit large strains readily provided of up to 1% associated with the AFE to FE phase transition. Electrostatic Conductive plates Low power Difficult to IJ02, IJ04 plates are separated by a consumption operate compressible or Many ink types electrostatic fluid dielectric can be used devices in an (usually air). Upon Fast operation aqueous application of a environment voltage, the plates The attract each other electrostatic and displace ink, actuator will causing drop normally need to ejection. The be separated from conductive plates the ink may be in a comb or Very large area honeycomb required to structure, or stacked achieve high to increase the forces surface area and High voltage therefore the force. drive transistors may be required Full pagewidth print heads are not competitive due to actuator size Electrostatic A strong electric Low current High voltage 1989 Saito et pull field is applied to consumption required al, U.S. Pat. No. 4,799,068 on ink the ink, whereupon Low May be 1989 Miura et electrostatic temperature damaged by al, U.S. Pat. No. 4,810,954 attraction accelerates sparks due to air Tone-jet the ink towards the breakdown print medium. Required field strength increases as the drop size decreases High voltage drive transistors required Electrostatic field attracts dust Permanent An electromagnet Low power Complex IJ07, IJ10 magnet directly attracts a consumption fabrication electro- permanent magnet, Many ink types Permanent magnetic displacing ink and can be used magnetic material causing drop Fast operation such as ejection. Rare earth High efficiency Neodymium Iron magnets with a field Easy extension Boron (NdFeB) strength around 1 from single required. Tesla can be used. nozzles to High local Examples are: pagewidth print currents required Samarium Cobalt heads Copper (SaCo) and metalization magnetic materials should be used for in the neodymium long iron boron family electromigration (NdFeB, lifetime and low NdDyFeBNb, resistivity NdDyFeB, etc) Pigmented inks are usually infeasible Operating temperature limited to the Curie temperature (around 540 K) Soft A solenoid induced Low power Complex IJ01, IJ05, IJ08, magnetic a magnetic field in a consumption fabrication IJ10, IJ12, IJ14, core soft magnetic core Many ink types Materials not IJ15, IJ17 electro- or yoke fabricated can be used usually present in magnetic from a ferrous Fast operation a CMOS fab such material such as High efficiency as NiFe, CoNiFe, electroplated iron Easy extension or CoFe are alloys such as from single required CoNiFe [1], CoFe, nozzles to High local or NiFe alloys. pagewidth print currents required Typically, the soft heads Copper magnetic material is metalization in two parts, which should be used for are normally held long apart by a spring. electromigration When the solenoid is lifetime and low actuated, the two resistivity parts attract, Electroplating displacing the ink. is required High saturation flux density is required (2.0-2.1 T is achievable with CoNiFe [1]) Lorenz The Lorenz force Low power Force acts as a IJ06, IJ11, IJ13, force acting on a current consumption twisting motion IJ16 carrying wire in a Many ink types Typically, only magnetic field is can be used a quarter of the utilized. Fast operation solenoid length This allows the High efficiency provides force in a magnetic field to be Easy extension useful direction supplied externally from single High local to the print head, for nozzles to currents required example with rare pagewidth print Copper earth permanent heads metalization magnets. should be used for Only the current long carrying wire need electromigration be fabricated on the lifetime and low print-head, resistivity simplifying Pigmented inks materials are usually requirements. infeasible Magneto- The actuator uses Many ink types Force acts as a Fischenbeck, striction the giant can be used twisting motion U.S. Pat. No. 4,032,929 magnetostrictive Fast operation Unusual IJ25 effect of materials Easy extension materials such as such as Terfenol-D from single Terfenol-D are (an alloy of terbium, nozzles to required dysprosium and iron pagewidth print High local developed at the heads currents required Naval Ordnance High force is Copper Laboratory, hence available metalization Ter-Fe-NOL). For should be used for best efficiency, the long actuator should be electromigration pre-stressed to lifetime and low approx. 8 MPa. resistivity Pre-stressing may be required Surface Ink under positive Low power Requires Silverbrook, EP tension pressure is held in a consumption supplementary 0771 658 A2 and reduction nozzle by surface Simple force to effect related patent tension. The surface construction drop separation applications tension of the ink is No unusual Requires reduced below the materials required special ink bubble threshold, in fabrication surfactants causing the ink to High efficiency Speed may be egress from the Easy extension limited by nozzle. from single surfactant nozzles to properties pagewidth print heads Viscosity The ink viscosity is Simple Requires Silverbrook, EP reduction locally reduced to construction supplementary 0771 658 A2 and select which drops No unusual force to effect related patent are to be ejected. A materials required drop separation applications viscosity reduction in fabrication Requires can be achieved Easy extension special ink electrothermally from single viscosity with most inks, but nozzles to properties special inks can be pagewidth print High speed is engineered for a heads difficult to 100:1 viscosity achieve reduction. Requires oscillating ink pressure A high temperature difference (typically 80 degrees) is required Acoustic An acoustic wave is Can operate Complex drive 1993 generated and without a nozzle circuitry Hadimioglu et al, focussed upon the plate Complex EUP 550,192 drop ejection region. fabrication 1993 Elrod et Low efficiency al, EUP 572,220 Poor control of drop position Poor control of drop volume Thermo- An actuator which Low power Efficient IJ03, IJ09, IJ17, elastic relies upon consumption aqueous operation IJ18, IJ19, IJ20, bend differential thermal Many ink types requires a thermal IJ21, IJ22, IJ23, actuator expansion upon can be used insulator on the IJ24, IJ27, IJ28, Joule heating is Simple planar hot side IJ29, IJ30, IJ31, used. fabrication Corrosion IJ32, IJ33, IJ34, Small chip area prevention can be IJ35, IJ36, IJ37, required for each difficult IJ38, IJ39, IJ40, actuator Pigmented inks IJ41 Fast operation may be infeasible, High efficiency as pigment CMOS particles may jam compatible the bend actuator voltages and currents Standard MEMS processes can be used Easy extension from single nozzles to pagewidth print heads High CTE A material with a High force can Requires IJ09, IJ17, IJ18, thermo- very high coefficient be generated special material IJ20, IJ21, IJ22, elastic of thermal Three methods (e.g. PTFE) IJ23, IJ24, IJ27, actuator expansion (CTE) of PTFE Requires a IJ28, IJ29, IJ30, such as deposition are PTFE deposition IJ31, IJ42, IJ43, polytetrafluoroethylene under process, which is IJ44 (PTFE) is used. development: not yet standard in As high CTE chemical vapor ULSI fabs materials are usually deposition (CVD), PTFE non-conductive, a spin coating, and deposition cannot heater fabricated evaporation be followed with from a conductive PTFE is a high temperature material is candidate for low (above 350° C.) incorporated. A 50 μm dielectric constant processing long PTFE bend insulation in ULSI Pigmented inks actuator with Very low may be infeasible, polysilicon heater power as pigment and 15 mW power consumption particles may jam input can provide Many ink types the bend actuator 180 μN force and 10 μm can be used deflection. Simple planar Actuator motions fabrication include: Small chip area Bend required for each Push actuator Buckle Fast operation Rotate High efficiency CMOS compatible voltages and currents Easy extension from single nozzles to pagewidth print heads Conductive A polymer with a High force can Requires IJ24 polymer high coefficient of be generated special materials thermo- thermal expansion Very low development elastic (such as PTFE) is power (High CTE actuator doped with consumption conductive conducting Many ink types polymer) substances to can be used Requires a increase its Simple planar PTFE deposition conductivity to fabrication process, which is about 3 orders of Small chip area not yet standard in magnitude below required for each ULSI fabs that of copper. The actuator PTFE conducting polymer Fast operation deposition cannot expands when High efficiency be followed with resistively heated. CMOS high temperature Examples of compatible (above 350° C.) conducting dopants voltages and processing include: currents Evaporation Carbon nanotubes Easy extension and CVD Metal fibers from single deposition Conductive nozzles to techniques cannot polymers such as pagewidth print be used doped polythiophene heads Pigmented inks Carbon granules may be infeasible, as pigment particles may jam the bend actuator Shape A shape memory High force is Fatigue limits IJ26 memory alloy such as TiNi available (stresses maximum number alloy (also known as of hundreds of of cycles Nitinol - Nickel MPa) Low strain Titanium alloy Large strain is (1%) is required to developed at the available (more extend fatigue Naval Ordnance than 3%) resistance Laboratory) is High corrosion Cycle rate thermally switched resistance limited by heat between its weak Simple removal martensitic state and construction Requires its high stiffness Easy extension unusual materials austenic state. The from single (TiNi) shape of the actuator nozzles to The latent heat in its martensitic pagewidth print of transformation state is deformed heads must be provided relative to the Low voltage High current austenic shape. The operation operation shape change causes Requires pre- ejection of a drop. stressing to distort the martensitic state Linear Linear magnetic Linear Requires IJ12 Magnetic actuators include the Magnetic unusual Actuator Linear Induction actuators can be semiconductor Actuator (LIA), constructed with materials such as Linear Permanent high thrust, long soft magnetic Magnet travel, and high alloys (e.g. Synchronous efficiency using CoNiFe) Actuator (LPMSA), planar Some varieties Linear Reluctance semiconductor also require Synchronous fabrication permanent Actuator (LRSA), techniques magnetic Linear Switched Long actuator materials such as Reluctance Actuator travel is available Neodymium iron (LSRA), and the Medium force boron (NdFeB) Linear Stepper is available Requires Actuator (LSA). Low voltage complex multi- operation phase drive circuitry High current operation

BASIC OPERATION MODE Description Advantages Disadvantages Examples Actuator This is the simplest Simple Drop repetition Thermal ink jet directly mode of operation: operation rate is usually Piezoelectric pushes ink the actuator directly No external limited to around ink jet supplies sufficient fields required 10 kHz. However, IJ01, IJ02, IJ03, kinetic energy to Satellite drops this is not IJ04, IJ05, IJ06, expel the drop. The can be avoided if fundamental to the IJ07, IJ09, IJ11, drop must have a drop velocity is method, but is IJ12, IJ14, IJ16, sufficient velocity to less than 4 m/s related to the refill IJ20, IJ22, IJ23, overcome the Can be method normally IJ24, IJ25, IJ26, surface tension. efficient, used IJ27, IJ28, IJ29, depending upon All of the drop IJ30, IJ31, IJ32, the actuator used kinetic energy IJ33, IJ34, IJ35, must be provided IJ36, IJ37, IJ38, by the actuator IJ39, IJ40, IJ41, Satellite drops IJ42, IJ43, IJ44 usually form if drop velocity is greater than 4.5 m/s Proximity The drops to be Very simple Requires close Silverbrook, EP printed are selected print head proximity between 0771 658 A2 and by some manner fabrication can be the print head and related patent (e.g. thermally used the print media or applications induced surface The drop transfer roller tension reduction of selection means May require pressurized ink). does not need to two print heads Selected drops are provide the energy printing alternate separated from the required to rows of the image ink in the nozzle by separate the drop Monolithic contact with the from the nozzle color print heads print medium or a are difficult transfer roller. Electrostatic The drops to be Very simple Requires very Silverbrook, EP pull printed are selected print head high electrostatic 0771 658 A2 and on ink by some manner fabrication can be field related patent (e.g. thermally used Electrostatic applications induced surface The drop field for small Tone-Jet tension reduction of selection means nozzle sizes is pressurized ink). does not need to above air Selected drops are provide the energy breakdown separated from the required to Electrostatic ink in the nozzle by separate the drop field may attract a strong electric from the nozzle dust field. Magnetic The drops to be Very simple Requires Silverbrook, EP pull on ink printed are selected print head magnetic ink 0771 658 A2 and by some manner fabrication can be Ink colors other related patent (e.g. thermally used than black are applications induced surface The drop difficult tension reduction of selection means Requires very pressurized ink). does not need to high magnetic Selected drops are provide the energy fields separated from the required to ink in the nozzle by separate the drop a strong magnetic from the nozzle field acting on the magnetic ink. Shutter The actuator moves High speed Moving parts IJ13, IJ17, IJ21 a shutter to block (>50 kHz) are required ink flow to the operation can be Requires ink nozzle. The ink achieved due to pressure pressure is pulsed at reduced refill time modulator a multiple of the Drop timing Friction and drop ejection can be very wear must be frequency. accurate considered The actuator Stiction is energy can be possible very low Shuttered The actuator moves Actuators with Moving parts IJ08, IJ15, IJ18, grill a shutter to block small travel can be are required IJ19 ink flow through a used Requires ink grill to the nozzle. Actuators with pressure The shutter small force can be modulator movement need only used Friction and be equal to the width High speed wear must be of the grill holes. (>50 kHz) considered operation can be Stiction is achieved possible Pulsed A pulsed magnetic Extremely low Requires an IJ10 magnetic field attracts an ‘ink energy operation external pulsed pull on ink pusher’ at the drop is possible magnetic field pusher ejection frequency. No heat Requires An actuator controls dissipation special materials a catch, which problems for both the prevents the ink actuator and the pusher from moving ink pusher when a drop is not to Complex be ejected. construction AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) None The actuator directly Simplicity of Drop ejection Most ink jets, fires the ink drop, construction energy must be including and there is no Simplicity of supplied by piezoelectric and external field or operation individual nozzle thermal bubble. other mechanism Small physical actuator IJ01, IJ02, IJ03, required. size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24, IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The ink pressure Oscillating ink Requires Silverbrook, EP ink oscillates, providing pressure can external ink 0771 658 A2 and pressure much of the drop provide a refill pressure oscillator related patent (including ejection energy. The pulse, allowing Ink pressure applications acoustic actuator selects higher operating phase and IJ08, IJ13, IJ15, stimulation) which drops are to speed amplitude must be IJ17, IJ18, IJ19, be fired by The actuators carefully IJ21 selectively blocking may operate with controlled or enabling nozzles. much lower Acoustic The ink pressure energy reflections in the oscillation may be Acoustic lenses ink chamber must achieved by can be used to be designed for vibrating the print focus the sound on head, or preferably the nozzles by an actuator in the ink supply. Media The print head is Low power Precision Silverbrook, EP proximity placed in close High accuracy assembly required 0771 658 A2 and proximity to the Simple print Paper fibers related patent print medium. head construction may cause applications Selected drops problems protrude from the Cannot print on print head further rough substrates than unselected drops, and contact the print medium. The drop soaks into the medium fast enough to cause drop separation. Transfer Drops are printed to High accuracy Bulky Silverbrook, EP roller a transfer roller Wide range of Expensive 0771 658 A2 and instead of straight to print substrates Complex related patent the print medium. A can be used construction applications transfer roller can Ink can be Tektronix hot also be used for dried on the melt piezoelectric proximity drop transfer roller ink jet separation. Any of the IJ series Electrostatic An electric field is Low power Field strength Silverbrook, EP used to accelerate Simple print required for 0771 658 A2 and selected drops head construction separation of related patent towards the print small drops is near applications medium. or above air Tone-Jet breakdown Direct A magnetic field is Low power Requires Silverbrook, EP magnetic used to accelerate Simple print magnetic ink 0771 658 A2 and field selected drops of head construction Requires strong related patent magnetic ink magnetic field applications towards the print medium. Cross The print head is Does not Requires IJ06, IJ16 magnetic placed in a constant require magnetic external magnet field magnetic field. The materials to be Current Lorenz force in a integrated in the densities may be current carrying print head high, resulting in wire is used to move manufacturing electromigration the actuator. process problems Pulsed A pulsed magnetic Very low Complex print IJ10 magnetic field is used to power operation is head construction field cyclically attract a possible Magnetic paddle, which Small print materials required pushes on the ink. A head size in print head small actuator moves a catch, which selectively prevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description Advantages Disadvantages Examples None No actuator Operational Many actuator Thermal mechanical simplicity mechanisms have Bubble Ink jet amplification is insufficient travel, IJ01, IJ02, IJ06, used. The actuator or insufficient IJ07, IJ16, IJ25, directly drives the force, to IJ26 drop ejection efficiently drive process. the drop ejection process Differential An actuator material Provides High stresses Piezoelectric expansion expands more on greater travel in a are involved IJ03, IJ09, IJ17, bend one side than on the reduced print head Care must be IJ18, IJ19, IJ20, actuator other. The expansion area taken that the IJ21, IJ22, IJ23, may be thermal, materials do not IJ24, IJ27, IJ29, piezoelectric, delaminate IJ30, IJ31, IJ32, magnetostrictive, or Residual bend IJ33, IJ34, IJ35, other mechanism. resulting from IJ36, IJ37, IJ38, The bend actuator high temperature IJ39, IJ42, IJ43, converts a high force or high stress IJ44 low travel actuator during formation mechanism to high travel, lower force mechanism. Transient A trilayer bend Very good High stresses IJ40, IJ41 bend actuator where the temperature are involved actuator two outside layers stability Care must be are identical. This High speed, as taken that the cancels bend due to a new drop can be materials do not ambient temperature fired before heat delaminate and residual stress. dissipates The actuator only Cancels responds to transient residual stress of heating of one side formation or the other. Reverse The actuator loads a Better coupling Fabrication IJ05, IJ11 spring spring. When the to the ink complexity actuator is turned High stress in off, the spring the spring releases. This can reverse the force/distance curve of the actuator to make it compatible with the force/time requirements of the drop ejection. Actuator A series of thin Increased travel Increased Some stack actuators are Reduced drive fabrication piezoelectric ink stacked. This can be voltage complexity jets appropriate where Increased IJ04 actuators require possibility of short high electric field circuits due to strength, such as pinholes electrostatic and piezoelectric actuators. Multiple Multiple smaller Increases the Actuator forces IJ12, IJ13, IJ18, actuators actuators are used force available may not add IJ20, IJ22, IJ28, simultaneously to from an actuator linearly, reducing IJ42, IJ43 move the ink. Each Multiple efficiency actuator need actuators can be provide only a positioned to portion of the force control ink flow required. accurately Linear A linear spring is Matches low Requires print IJ15 Spring used to transform a travel actuator head area for the motion with small with higher travel spring travel and high force requirements into a longer travel, Non-contact lower force motion. method of motion transformation Coiled A bend actuator is Increases travel Generally IJ17, IJ21, IJ34, actuator coiled to provide Reduces chip restricted to planar IJ35 greater travel in a area implementations reduced chip area. Planar due to extreme implementations fabrication are relatively easy difficulty in other to fabricate. orientations. Flexure A bend actuator has Simple means Care must be IJ10, IJ19, IJ33 bend a small region near of increasing taken not to actuator the fixture point, travel of a bend exceed the elastic which flexes much actuator limit in the flexure more readily than area the remainder of the Stress actuator. The distribution is actuator flexing is very uneven effectively Difficult to converted from an accurately model even coiling to an with finite angular bend, element analysis resulting in greater travel of the actuator tip. Catch The actuator Very low Complex IJ10 controls a small actuator energy construction catch. The catch Very small Requires either enables or actuator size external force disables movement Unsuitable for of an ink pusher that pigmented inks is controlled in a bulk manner. Gears Gears can be used to Low force, low Moving parts IJ13 increase travel at the travel actuators are required expense of duration. can be used Several Circular gears, rack Can be actuator cycles are and pinion, ratchets, fabricated using required and other gearing standard surface More complex methods can be MEMS processes drive electronics used. Complex construction Friction, friction, and wear are possible Buckle A buckle plate can Very fast Must stay S. Hirata et al, plate be used to change a movement within elastic “An Ink-jet Head slow actuator into a achievable limits of the Using Diaphragm fast motion. It can materials for long Microactuator”, also convert a high device life Proc. IEEE force, low travel High stresses MEMS, February actuator into a high involved 1996, pp 418-423. travel, medium force Generally high IJ18, IJ27 motion. power requirement Tapered A tapered magnetic Linearizes the Complex IJ14 magnetic pole can increase magnetic construction pole travel at the expense force/distance of force. curve Lever A lever and fulcrum Matches low High stress IJ32, IJ36, IJ37 is used to transform travel actuator around the a motion with small with higher travel fulcrum travel and high force requirements into a motion with Fulcrum area longer travel and has no linear lower force. The movement, and lever can also can be used for a reverse the direction fluid seal of travel. Rotary The actuator is High Complex IJ28 impeller connected to a rotary mechanical construction impeller. A small advantage Unsuitable for angular deflection of The ratio of pigmented inks the actuator results force to travel of in a rotation of the the actuator can be impeller vanes, matched to the which push the ink nozzle against stationary requirements by vanes and out of the varying the nozzle. number of impeller vanes Acoustic A refractive or No moving Large area 1993 lens diffractive (e.g. zone parts required Hadimioglu et al, plate) acoustic lens Only relevant EUP 550,192 is used to for acoustic ink 1993 Elrod et concentrate sound jets al, EUP 572,220 waves. Sharp A sharp point is Simple Difficult to Tone-jet conductive used to concentrate construction fabricate using point an electrostatic field. standard VLSI processes for a surface ejecting ink-jet Only relevant for electrostatic ink jets

ACTUATOR MOTION Description Advantages Disadvantages Examples Volume The volume of the Simple High energy is Hewlett- expansion actuator changes, construction in the typically required Packard Thermal pushing the ink in case of thermal to achieve volume Ink jet all directions. ink jet expansion. This Canon leads to thermal Bubblejet stress, cavitation, and kogation in thermal ink jet implementations Linear, The actuator moves Efficient High IJ01, IJ02, IJ04, normal to in a direction normal coupling to ink fabrication IJ07, IJ11, IJ14 chip to the print head drops ejected complexity may surface surface. The nozzle normal to the be required to is typically in the surface achieve line of movement. perpendicular motion Parallel to The actuator moves Suitable for Fabrication IJ12, IJ13, IJ15, chip parallel to the print planar fabrication complexity IJ33,, IJ34, IJ35, surface head surface. Drop Friction IJ36 ejection may still be Stiction normal to the surface. Membrane An actuator with a The effective Fabrication 1982 Howkins push high force but small area of the complexity U.S. Pat. No. 4,459,601 area is used to push actuator becomes Actuator size a stiff membrane the membrane Difficulty of that is in contact area integration in a with the ink. VLSI process Rotary The actuator causes Rotary levers Device IJ05, IJ08, IJ13, the rotation of some may be used to complexity IJ28 element, such a grill increase travel May have or impeller Small chip area friction at a pivot requirements point Bend The actuator bends A very small Requires the 1970 Kyser et when energized. change in actuator to be al U.S. Pat. No. 3,946,398 This may be due to dimensions can be made from at least 1973 Stemme differential thermal converted to a two distinct U.S. Pat. No. 3,747,120 expansion, large motion. layers, or to have IJ03, IJ09, IJ10, piezoelectric a thermal IJ19, IJ23, IJ24, expansion, difference across IJ25, IJ29, IJ30, magnetostriction, or the actuator IJ31, IJ33, IJ34, other form of IJ35 relative dimensional change. Swivel The actuator swivels Allows Inefficient IJ06 around a central operation where coupling to the ink pivot. This motion is the net linear force motion suitable where there on the paddle is are opposite forces zero applied to opposite Small chip area sides of the paddle, requirements e.g. Lorenz force. Straighten The actuator is Can be used Requires IJ26, IJ32 normally bent, and with shape careful balance of straightens when memory alloys stresses to ensure energized. where the austenic that the quiescent phase is planar bend is accurate Double The actuator bends One actuator Difficult to IJ36, IJ37, IJ38 bend in one direction can be used to make the drops when one element is power two ejected by both energized, and bends nozzles. bend directions the other way when Reduced chip identical. another element is size. A small energized. Not sensitive to efficiency loss ambient compared to temperature equivalent single bend actuators. Shear Energizing the Can increase Not readily 1985 Fishbeck actuator causes a the effective travel applicable to other U.S. Pat. No. 4,584,590 shear motion in the of piezoelectric actuator actuator material. actuators mechanisms Radial The actuator Relatively easy High force 1970 Zoltan constriction squeezes an ink to fabricate single required U.S. Pat. No. 3,683,212 reservoir, forcing nozzles from glass Inefficient ink from a tubing as Difficult to constricted nozzle. macroscopic integrate with structures VLSI processes Coil/ A coiled actuator Easy to Difficult to IJ17, IJ21, IJ34, uncoil uncoils or coils more fabricate as a fabricate for non- IJ35 tightly. The motion planar VLSI planar devices of the free end of the process Poor out-of- actuator ejects the Small area plane stiffness ink. required, therefore low cost Bow The actuator bows Can increase Maximum IJ16, IJ18, IJ27 (or buckles) in the the speed of travel travel is middle when Mechanically constrained energized. rigid High force required Push-Pull Two actuators The structure is Not readily IJ18 control a shutter. pinned at both suitable for ink One actuator pulls ends, so has a high jets which directly the shutter, and the out-of-plane push the ink other pushes it. rigidity Curl A set of actuators Good fluid flow Design IJ20, IJ42 inwards curl inwards to to the region complexity reduce the volume behind the of ink that they actuator increases enclose. efficiency Curl A set of actuators Relatively Relatively large IJ43 outwards curl outwards, simple chip area pressurizing ink in a construction chamber surrounding the actuators, and expelling ink from a nozzle in the chamber. Iris Multiple vanes High efficiency High IJ22 enclose a volume of Small chip area fabrication ink. These complexity simultaneously Not suitable for rotate, reducing the pigmented inks volume between the vanes. Acoustic The actuator The actuator Large area 1993 vibration vibrates at a high can be physically required for Hadimioglu et al, frequency. distant from the efficient operation EUP 550,192 ink at useful 1993 Elrod et frequencies al, EUP 572,220 Acoustic coupling and crosstalk Complex drive circuitry Poor control of drop volume and position None In various ink jet No moving Various other Silverbrook, EP designs the actuator parts tradeoffs are 0771 658 A2 and does not move. required to related patent eliminate moving applications parts Tone-jet

NOZZLE REFILL METHOD Description Advantages Disadvantages Examples Surface This is the normal Fabrication Low speed Thermal ink jet tension way that ink jets are simplicity Surface tension Piezoelectric refilled. After the Operational force relatively ink jet actuator is simplicity small compared to IJ01-IJ07, IJ10-IJ14, energized, it actuator force IJ16, IJ20, typically returns Long refill time IJ22-IJ45 rapidly to its normal usually dominates position. This rapid the total repetition return sucks in air rate through the nozzle opening. The ink surface tension at the nozzle then exerts a small force restoring the meniscus to a minimum area. This force refills the nozzle. Shuttered Ink to the nozzle High speed Requires IJ08, IJ13, IJ15, oscillating chamber is provided Low actuator common ink IJ17, IJ18, IJ19, ink at a pressure that energy, as the pressure oscillator IJ21 pressure oscillates at twice actuator need only May not be the drop ejection open or close the suitable for frequency. When a shutter, instead of pigmented inks drop is to be ejected, ejecting the ink the shutter is opened drop for 3 half cycles: drop ejection, actuator return, and refill. The shutter is then closed to prevent the nozzle chamber emptying during the next negative pressure cycle. Refill After the main High speed, as Requires two IJ09 actuator actuator has ejected the nozzle is independent a drop a second actively refilled actuators per (refill) actuator is nozzle energized. The refill actuator pushes ink into the nozzle chamber. The refill actuator returns slowly, to prevent its return from emptying the chamber again. Positive The ink is held a High refill rate, Surface spill Silverbrook, EP ink slight positive therefore a high must be prevented 0771 658 A2 and pressure pressure. After the drop repetition Highly related patent ink drop is ejected, rate is possible hydrophobic print applications the nozzle chamber head surfaces are Alternative for:, fills quickly as required IJ01-IJ07, IJ10-IJ14, surface tension and IJ16, IJ20, ink pressure both IJ22-IJ45 operate to refill the nozzle.

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description Advantages Disadvantages Examples Long inlet The ink inlet Design Restricts refill Thermal ink jet channel channel to the simplicity rate Piezoelectric nozzle chamber is Operational May result in a ink jet made long and simplicity relatively large IJ42, IJ43 relatively narrow, Reduces chip area relying on viscous crosstalk Only partially drag to reduce inlet effective back-flow. Positive The ink is under a Drop selection Requires a Silverbrook, EP ink positive pressure, so and separation method (such as a 0771 658 A2 and pressure that in the quiescent forces can be nozzle rim or related patent state some of the ink reduced effective applications drop already Fast refill time hydrophobizing, Possible protrudes from the or both) to prevent operation of the nozzle. flooding of the following: IJ01-IJ07, This reduces the ejection surface of IJ09-IJ12, pressure in the the print head. IJ14, IJ16, IJ20, nozzle chamber IJ22,, IJ23-IJ34, which is required to IJ36-IJ41, IJ44 eject a certain volume of ink. The reduction in chamber pressure results in a reduction in ink pushed out through the inlet. Baffle One or more baffles The refill rate is Design HP Thermal are placed in the not as restricted as complexity Ink Jet inlet ink flow. When the long inlet May increase Tektronix the actuator is method. fabrication piezoelectric ink energized, the rapid Reduces complexity (e.g. jet ink movement crosstalk Tektronix hot melt creates eddies which Piezoelectric print restrict the flow heads). through the inlet. The slower refill process is unrestricted, and does not result in eddies. Flexible In this method Significantly Not applicable Canon flap recently disclosed reduces back-flow to most ink jet restricts by Canon, the for edge-shooter configurations inlet expanding actuator thermal ink jet Increased (bubble) pushes on a devices fabrication flexible flap that complexity restricts the inlet. Inelastic deformation of polymer flap results in creep over extended use Inlet filter A filter is located Additional Restricts refill IJ04, IJ12, IJ24, between the ink inlet advantage of ink rate IJ27, IJ29, IJ30 and the nozzle filtration May result in chamber. The filter Ink filter may complex has a multitude of be fabricated with construction small holes or slots, no additional restricting ink flow. process steps The filter also removes particles which may block the nozzle. Small inlet The ink inlet Design Restricts refill IJ02, IJ37, IJ44 compared channel to the simplicity rate to nozzle nozzle chamber has May result in a a substantially relatively large smaller cross section chip area than that of the Only partially nozzle, resulting in effective easier ink egress out of the nozzle than out of the inlet. Inlet A secondary Increases speed Requires IJ09 shutter actuator controls the of the ink-jet print separate refill position of a shutter, head operation actuator and drive closing off the ink circuit inlet when the main actuator is energized. The inlet is The method avoids Back-flow Requires IJ01, IJ03, located the problem of inlet problem is careful design to 1J05, IJ06, IJ07, behind the back-flow by eliminated minimize the IJ10, IJ11, IJ14, ink- arranging the ink- negative pressure IJ16, IJ22, IJ23, pushing pushing surface of behind the paddle IJ25, IJ28, IJ31, surface the actuator between IJ32, IJ33, IJ34, the inlet and the IJ35, IJ36, IJ39, nozzle. IJ40, IJ41 Part of the The actuator and a Significant Small increase IJ07, IJ20, IJ26, actuator wall of the ink reductions in in fabrication IJ38 moves to chamber are back-flow can be complexity shut off arranged so that the achieved the inlet motion of the Compact actuator closes off designs possible the inlet. Nozzle In some Ink back-flow None related to Silverbrook, EP actuator configurations of ink problem is ink back-flow on 0771 658 A2 and does not jet, there is no eliminated actuation related patent result in expansion or applications ink back- movement of an Valve-jet flow actuator which may Tone-jet cause ink back-flow through the inlet.

NOZZLE CLEARING METHOD Description Advantages Disadvantages Examples Normal All of the nozzles No added May not be Most ink jet nozzle are fired complexity on the sufficient to systems firing periodically, before print head displace dried ink IJ01, IJ02, IJ03, the ink has a chance IJ04, IJ05, IJ06, to dry. When not in IJ07, IJ09, IJ10, use the nozzles are IJ11, IJ12, IJ14, sealed (capped) IJ16, IJ20, IJ22, against air. IJ23, IJ24, IJ25, The nozzle firing is IJ26, IJ27, IJ28, usually performed IJ29, IJ30, IJ31, during a special IJ32, IJ33, IJ34, clearing cycle, after IJ36, IJ37, IJ38, first moving the IJ39, IJ40,, IJ41, print head to a IJ42, IJ43, IJ44,, cleaning station. IJ45 Extra In systems which Can be highly Requires higher Silverbrook, EP power to heat the ink, but do effective if the drive voltage for 0771 658 A2 and ink heater not boil it under heater is adjacent clearing related patent normal situations, to the nozzle May require applications nozzle clearing can larger drive be achieved by over- transistors powering the heater and boiling ink at the nozzle. Rapid The actuator is fired Does not Effectiveness May be used succession in rapid succession. require extra drive depends with: IJ01, IJ02, of actuator In some circuits on the substantially upon IJ03, IJ04, IJ05, pulses configurations, this print head the configuration IJ06, IJ07, IJ09, may cause heat Can be readily of the ink jet IJ10, IJ11, IJ14, build-up at the controlled and nozzle IJ16, IJ20, IJ22, nozzle which boils initiated by digital IJ23, IJ24, IJ25, the ink, clearing the logic IJ27, IJ28, IJ29, nozzle. In other IJ30, IJ31, IJ32, situations, it may IJ33, IJ34, IJ36, cause sufficient IJ37, IJ38, IJ39, vibrations to IJ40, IJ41, IJ42, dislodge clogged IJ43, IJ44, IJ45 nozzles. Extra Where an actuator is A simple Not suitable May be used power to not normally driven solution where where there is a with: IJ03, IJ09, ink to the limit of its applicable hard limit to IJ16, IJ20, IJ23, pushing motion, nozzle actuator IJ24, IJ25, IJ27, actuator clearing may be movement IJ29, IJ30, IJ31, assisted by IJ32, IJ39, IJ40, providing an IJ41, IJ42, IJ43, enhanced drive IJ44, IJ45 signal to the actuator. Acoustic An ultrasonic wave A high nozzle High IJ08, IJ13, IJ15, resonance is applied to the ink clearing capability implementation IJ17, IJ18, IJ19, chamber. This wave can be achieved cost if system IJ21 is of an appropriate May be does not already amplitude and implemented at include an frequency to cause very low cost in acoustic actuator sufficient force at systems which the nozzle to clear already include blockages. This is acoustic actuators easiest to achieve if the ultrasonic wave is at a resonant frequency of the ink cavity. Nozzle A microfabricated Can clear Accurate Silverbrook, EP clearing plate is pushed severely clogged mechanical 0771 658 A2 and plate against the nozzles. nozzles alignment is related patent The plate has a post required applications for every nozzle. A Moving parts post moves through are required each nozzle, There is risk of displacing dried ink. damage to the nozzles Accurate fabrication is required Ink The pressure of the May be Requires May be used pressure ink is temporarily effective where pressure pump or with all IJ series pulse increased so that ink other methods other pressure ink jets streams from all of cannot be used actuator the nozzles. This Expensive may be used in Wasteful of ink conjunction with actuator energizing. Print head A flexible ‘blade’ is Effective for Difficult to use Many ink jet wiper wiped across the planar print head if print head systems print head surface. surfaces surface is non- The blade is usually Low cost planar or very fabricated from a fragile flexible polymer, Requires e.g. rubber or mechanical parts synthetic elastomer. Blade can wear out in high volume print systems Separate A separate heater is Can be Fabrication Can be used ink boiling provided at the effective where complexity with many IJ heater nozzle although the other nozzle series ink jets normal drop e- clearing methods ection mechanism cannot be used does not require it. Can be The heaters do not implemented at no require individual additional cost in drive circuits, as some ink jet many nozzles can be configurations cleared simultaneously, and no imaging is required.

NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages Examples Electroformed A nozzle plate is Fabrication High Hewlett nickel separately fabricated simplicity temperatures and Packard Thermal from electroformed pressures are Ink jet nickel, and bonded required to bond to the print head nozzle plate chip. Minimum thickness constraints Differential thermal expansion Laser Individual nozzle No masks Each hole must Canon ablated or holes are ablated by required be individually Bubblejet drilled an intense UV laser Can be quite formed 1988 Sercel et polymer in a nozzle plate, fast Special al., SPIE, Vol. 998 which is typically a Some control equipment Excimer Beam polymer such as over nozzle required Applications, pp. polyimide or profile is possible Slow where 76-83 polysulphone Equipment there are many 1993 Watanabe required is thousands of et al., U.S. Pat. No. relatively low cost nozzles per print 5,208,604 head May produce thin burrs at exit holes Silicon A separate nozzle High accuracy Two part K. Bean, IEEE micromachined plate is is attainable construction Transactions on micromachined from High cost Electron Devices, single crystal Requires Vol. ED-25, No. silicon, and bonded precision 10, 1978, pp to the print head alignment 1185-1195 wafer. Nozzles may be Xerox 1990 clogged by Hawkins et al., adhesive U.S. Pat. No. 4,899,181 Glass Fine glass capillaries No expensive Very small 1970 Zoltan capillaries are drawn from glass equipment nozzle sizes are U.S. Pat. No. 3,683,212 tubing. This method required difficult to form has been used for Simple to make Not suited for making individual single nozzles mass production nozzles, but is difficult to use for bulk manufacturing of print heads with thousands of nozzles. Monolithic, The nozzle plate is High accuracy Requires Silverbrook, EP surface deposited as a layer (<1 μm) sacrificial layer 0771 658 A2 and micromachined using standard VLSI Monolithic under the nozzle related patent using deposition Low cost plate to form the applications VLSI techniques. Nozzles Existing nozzle chamber IJ01, IJ02, IJ04, litho- are etched in the processes can be Surface may be IJ11, IJ12, IJ17, graphic nozzle plate using used fragile to the IJ18, IJ20, IJ22, processes VLSI lithography touch IJ24, IJ27, IJ28, and etching. IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Monolithic, The nozzle plate is a High accuracy Requires long IJ03, IJ05, IJ06, etched buried etch stop in (<1 μm) etch times IJ07, IJ08, IJ09, through the wafer. Nozzle Monolithic Requires a IJ10, IJ13, IJ14, substrate chambers are etched Low cost support wafer IJ15, IJ16, IJ19, in the front of the No differential IJ21, IJ23, IJ25, wafer, and the wafer expansion IJ26 is thinned from the back side. Nozzles are then etched in the etch stop layer. No nozzle Various methods No nozzles to Difficult to Ricoh 1995 plate have been tried to become clogged control drop Sekiya et al U.S. Pat. No. eliminate the position 5,412,413 nozzles entirely, to accurately 1993 prevent nozzle Crosstalk Hadimioglu et al clogging. These problems EUP 550,192 include thermal 1993 Elrod et al bubble mechanisms EUP 572,220 and acoustic lens mechanisms Trough Each drop ejector Reduced Drop firing IJ35 has a trough through manufacturing direction is which a paddle complexity sensitive to moves. There is no Monolithic wicking. nozzle plate. Nozzle slit The elimination of No nozzles to Difficult to 1989 Saito et al instead of nozzle holes and become clogged control drop U.S. Pat. No. 4,799,068 individual replacement by a slit position nozzles encompassing many accurately actuator positions Crosstalk reduces nozzle problems clogging, but increases crosstalk due to ink surface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages Examples Edge Ink flow is along the Simple Nozzles limited Canon (‘edge surface of the chip, construction to edge Bubblejet 1979 shooter’) and ink drops are No silicon High resolution Endo et al GB ejected from the etching required is difficult patent 2,007,162 chip edge. Good heat Fast color Xerox heater- sinking via printing requires in-pit 1990 substrate one print head per Hawkins et al Mechanically color U.S. Pat. No. 4,899,181 strong Tone-jet Ease of chip handing Surface Ink flow is along the No bulk silicon Maximum ink Hewlett- (‘roof surface of the chip, etching required flow is severely Packard TIJ 1982 shooter’) and ink drops are Silicon can restricted Vaught et al U.S. Pat. No. ejected from the make an effective 4,490,728 chip surface, normal heat sink IJ02, IJ11, IJ12, to the plane of the Mechanical IJ20, IJ22 chip. strength Through Ink flow is through High ink flow Requires bulk Silverbrook, EP chip, the chip, and ink Suitable for silicon etching 0771 658 A2 and forward drops are ejected pagewidth print related patent (‘up from the front heads applications shooter’) surface of the chip. High nozzle IJ04, IJ17, IJ18, packing density IJ24, IJ27-IJ45 therefore low manufacturing cost Through Ink flow is through High ink flow Requires wafer IJ01, IJ03, IJ05, chip, the chip, and ink Suitable for thinning IJ06, IJ07, IJ08, reverse drops are ejected pagewidth print Requires IJ09, IJ10, IJ13, (‘down from the rear surface heads special handling IJ14, IJ15, IJ16, shooter’) of the chip. High nozzle during IJ19, IJ21, IJ23, packing density manufacture IJ25, IJ26 therefore low manufacturing cost Through Ink flow is through Suitable for Pagewidth punt Epson Stylus actuator the actuator, which piezoelectric print heads require Tektronix hot is not fabricated as heads several thousand melt piezoelectric part of the same connections to ink jets substrate as the drive drive circuits transistors. Cannot be manufactured in standard CMOS fabs Complex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Water based ink Environmentally Slow drying Most existing dye which typically friendly Corrosive ink jets contains: water, dye, No odor Bleeds on paper All IJ series ink surfactant, May jets humectant, and strikethrough Silverbrook, EP biocide. Cockles paper 0771 658 A2 and Modern ink dyes related patent have high water- applications fastness, light fastness Aqueous, Water based ink Environmentally Slow drying IJ02, IJ04, IJ21, pigment which typically friendly Corrosive IJ26, IJ27, IJ30 contains: water, No odor Pigment may Silverbrook, EP pigment, surfactant, Reduced bleed clog nozzles 0771 658 A2 and humectant, and Reduced Pigment may related patent biocide. wicking clog actuator applications Pigments have an Reduced mechanisms Piezoelectric advantage in strikethrough Cockles paper ink-jets reduced bleed, Thermal ink wicking and jets (with strikethrough. significant restrictions) Methyl MEK is a highly Very fast Odorous All IJ series ink Ethyl volatile solvent used drying Flammable jets Ketone for industrial Prints on (MEK) printing on difficult various substrates surfaces such as such as metals and aluminum cans. plastics Alcohol Alcohol based inks Fast drying Slight odor All IJ series ink (ethanol, can be used where Operates at Flammable jets 2-butanol, the printer must sub-freezing and operate at temperatures others) temperatures below Reduced paper the freezing point of cockle water. An example Low cost of this is in-camera consumer photographic printing. Phase The ink is solid at No drying time- High viscosity Tektronix hot change room temperature, ink instantly Printed ink melt piezoelectric (hot melt) and is melted in the freezes on the typically has a ink jets print head before print medium ‘waxy’ feel 1989 Nowak jetting. Hot melt Almost any Printed pages U.S. Pat. No. 4,820,346 inks are usually wax print medium can may ‘block’ All IJ series ink based, with a be used Ink temperature jets melting point around No paper may be above the 80° C. After jetting cockle occurs curie point of the ink freezes No wicking permanent almost instantly occurs magnets upon contacting the No bleed Ink heaters print medium or a occurs consume power transfer roller. No Long warm-up strikethrough time occurs Oil Oil based inks are High solubility High viscosity: All IJ series ink extensively used in medium for some this is a significant jets offset printing. They dyes limitation for use have advantages in Does not cockle in ink jets, which improved paper usually require a characteristics on Does not wick low viscosity. paper (especially no through paper Some short chain wicking or cockle). and multi- Oil soluble dies and branched oils have pigments are a sufficiently low required. viscosity. Slow drying Microemulsion A microemulsion is Stops ink bleed Viscosity All IJ series ink a stable, self High dye higher than water jets forming emulsion of solubility Cost is slightly oil, water, and Water, oil, and higher than water surfactant. The amphiphilic based ink characteristic drop soluble dies can High surfactant size is less than 100 nm, be used concentration and is Can stabilize required (around determined by the pigment 5%) preferred curvature suspensions of the surfactant. 

1. An ink ejection nozzle comprising: an ink reservoir with an oscillator configured to oscillate ink pressure in the reservoir; a wafer assembly defining an ink supply channel in fluid communication with the ink reservoir; a nozzle chamber structure on the wafer assembly and defining a nozzle chamber in fluid communication with the ink supply channel, and an ink ejection port in fluid communication with the nozzle chamber; and a shutter positioned in the nozzle chamber and configured to shut the ink ejection port to the ejection of ink from the nozzle chamber.
 2. An ink ejection nozzle as claimed in claim 1, wherein the oscillator includes an ultrasonic transducer.
 3. An ink ejection nozzle as claimed in claim 2, wherein the ultrasonic transducer includes a piezoelectric transducer.
 4. An ink ejection nozzle as claimed in claim 1, wherein the wafer assembly includes: a silicon wafer; a CMOS layer positioned on the silicon wafer; and a protective passivation layer positioned on the CMOS layer. 